If I sell the property for $10x 15 years later and want to use a 1031 Exchange, how can I differentiate my personal homestead from the larger acreage. 

Getting that done correctly is your most important task right now and give them notice could throw a wrench into it. 

It was in pretty good shape overall for its age having had various updates through the years,  but in a perfect world it was going to need work to correct awful floor plan (made by combining two small main floor units into a larger one) and the roof was going to need replacing in 5 years,  and it needed some other upgrades and modernizing if I was going to keep it longer.   

If the property is larger, the percentage will be less but the owner is now covering salaries for on-site personnel.

Hoping to put 5-10% down and house hack instead of the 20-25% down many larger banks require when you get to a 3rd/4th unit.

The above may not be possible if there are larger setbacks, parking, or driveway requirements.

With older homes, you need to have larger CapX budgets in order to account for the larger number of items that will need fixing.

If you have experience land lording it might be worth a try, but the task was too daunting for us and we never regretted getting a PM.

I would suggest that most investors put their money into investment real estate, not into making their primary house larger. 

You will have to keep trading up to larger properties.